L. Trouvelot— Veiled Solar Spots. 171 



one, it nevertheless presented many difficulties ; partly owing to 

 the minuteness and delicacy of these objects, partly on account 

 of the unsteadiness of the atmosphere, and partly to the many 

 defects caused by the great amount of heat concentrated at 

 the focus of the objective. However, the observations show 

 clearly that though the number of gray spots varies but very 

 little in different latitudes, in general the spots become larger 

 and more complicated as they approach the equatorial zones. 



The most marked characteristic of the gray spots is their 

 vagueness of outline. They are never sharply defined like 

 ordinary spots, but they appear blurred and diffused like an 

 object seen through a mist. As I shall endeavor to show 

 presently, these objects are really seen through chromospheric 

 gases which are spread as a veil over them, causing this vague- 

 ness of outline. For this reason, I propose for them the name 

 of Veihd Solar Spots. 



The veiled solar spots, especially in the lower latitudes, have 

 a remarkable tendency to assemble into small groups after the 

 manner of ordinary spots. Sometimes three or four are seen in 

 contact, while there are comparatively large intervals where 

 none are to be seen. I have in several instances seen the 

 actual formation into groups of distinct veiled spots. 



The granulations of the chromosphere are seen projected 

 upon the veiled spots, just as anywhere else, but they are not 

 there so regularly distributed; some being closely crowded 

 together, while others are widely scattered. Small faculas are 

 often formed in this manner by the aggregation of several 

 granules into one mass. Once in a while the granulations 

 appear as if they were under the power of a propelling force by 

 which they arrange themselves in files, and sometimes in 

 capricious "figures which are very remarkable. 



In many cases I have observed that the granulations pro- 

 jected upon the veiled spots have an extraordinary mobility, 

 to be seen nowhere else, except perhaps in the ^immediate 

 vicinity of ordinary spots in full activity. Often their form and 

 position are totallv changed within a few minutes, and some- 

 times even within a few seconds. This was especially the case 

 JuBe 21. At 8h 30"' on that day, I was observing a group of 

 veiled spots not far from the center of the sun, when my atten- 

 tion was drawn to the extraordinary mobility of the granulations 

 covering this group. In an instant they changed their form 

 and position, some crowding together as though briskly attract- 

 ing each other, while others would fly apart as if repelled by 

 an invisible force. Under this tumultuous conflict of forces, 

 new veiled spots would appear and disappear in an instant, 

 faculae would form and vanish ; in fact, all was in motion and 

 confusion on that particular part of the sun. It was evident 

 that immense forces were in conflict under the chromosphere. 



